1. Field of the Invention
The present invention relates generally to interfaces between dissimilar materials, and more particularly to interfaces in microelectronic circuits between substrates and metal surfaces possessing disparate temperature coefficients of expansion.
2. Description of the Prior Art
Large substrates comprising more than one square inch of surface area have conventionally, as in the microelectronics domain, been affixed to metal surfaces via epoxies, solders, or alloys. A substrate, such as alumina or beryllia, may possess a different temperature coefficient of expansion than the metal to which it is bonded. Accordingly, when the combination is subjected to thermal variations, the materials expand at disparate rates, often precipitating shearing of the bonding material or fracturing of the substrate. To ameliorate this result, industrial practice normally entails partitioning of large substrates into smaller substrates having surface areas less than one square inch.
Thus, there is a need for an apparatus that allows larges substrates to be mounted on metal surfaces without shearing of the interfaces and jeopardizing of the substrates, upon exposure to varying temperatures.